Implant-supported single crowns (SCs)

CHAPTER 6

Anterior regions

2.6.1 Anterior implant-supported SC with GBR

2.6.2 Anterior implant-supported SC with GBR

2.6.3 Anterior implant-supported SC

Posterior regions

2.6.4 Posterior implant-supported SC with GBR

2.6.5 Posterior implant-supported SC with GBR

2.6.6 Posterior implant-supported SC and optical impression

Complex situations

2.6.7 Tooth- and implant-supported all-ceramic SCs and fixed dental prostheses (FDPs)

2.6.1 Anterior implant-supported SC with GBR

■ Anterior single central incisor (all-ceramic abutment and restoration)

■ Single anterior implant with guided bone regeneration (GBR)

This first case shows the application of a regular diameter implant (bone level 4.1 mm) with a zirconia abutment and lithium-disilicate crown in the esthetic zone.

Assessment and treatment planning

A 42-year-old male patient presented himself at the clinic as he could sense a small movement in his endodontically treated central incisor 21 for several years prior. The patient was healthy, a non-smoker, and did not take any medication.

Evaluating the tooth during the first appointment, it became immediately evident that not only the metalceramic crown and the gold post had become loose, but also the root had a vertical fracture that made it irrational to treat (Fig 2-6-1).

Once it became evident that the tooth had to be extracted, the two main fixed restorative options were discussed with the patient. On the one hand, a single-retainer resin-bonded fixed dental prosthesis (RBFDP) bonded to tooth 11, or on the other, a single implant.

In this particular case, due to the rotation of his adjacent central incisor and the bite that had not sufficient horizontal overlap to place a zirconia backing, the decision was drawn toward placement of a regular diameter bone-level implant (ASTRA OsseoSpeed, Dentsply Sirona, Bensheim, Germany).

Before the extraction an alginate impression was performed and it was planned to prefabricate a provisional metal-based RBFDP with two small and very thin backings to offer the patient a fixed restoration directly on the day of extraction.

After a healing period of 8 weeks, an early implant placement procedure was planned. Due to the position in the arch and the available space, it was decided to place a bone-level implant with a regular diameter, including GBR if needed. After successful osseointegration and a provisional phase, the implant would be restored with a direct screw-retained restoration (Fig 2-6-2).

Provisionalization

The loose crown was provisionally cemented on the fractured root and two alginate impressions were performed. Those were sent to the dental laboratory and after the production of the plaster casts, the respective failing tooth was carved off.

A conventional denture tooth was selected according to the corresponding shape and to the basic Vita shade A2 (Creapearl, Creation Willi Geller, Meiningen, Austria).

The denture tooth had to be slightly adjusted to perfectly match the pontic before it was hollowed out from the palatal side to gain space for the supporting chrome cobalt metal framework.

Once the framework with these extremely thin backings (due to the lack of space) was cast and adjusted, the denture tooth was relined on the plaster cast with a classic acrylic PMMA material (New Outline, Anaxdent, Stuttgart, Germany) and finalized.

Additionally, two cementation aides (little holes) were carved into the backings (Fig 2-6-3).

Extraction

Due to the vertical fracture and despite an extremely careful extraction, the tooth immediately broke into several pieces. Once the tooth and the remaining root fragments were extracted, granulation tissue had to be removed and finally the socket was curettaged and rinsed with neomycin solution (Fig 2-6-4).

Ridge preservation

After the extraction and cleaning of the socket, a xenogeneic bone substitute (Bio-Oss Collagen, Geistlich, Wolhusen, Switzerland) was inserted in combination with a punch graft harvested from the palate to perform a ridge preservation. Once sutured, the fixed RBFDP provisional was adapted to the apical side to avoid any pressure on the graft and cemented (Fig 2-6-5).

Implant placement and regeneration

According to the diagnostics, a surgical stent was fabricated, transferring the prosthetic plan of the ideal three-dimensional (3D) position of the implant to the surgical intervention.

At the day of implant placement (4 months after extraction), the patient was premedicated with 1500 mg amoxicillin and 600 mg ibuprofen. After the raising of a mucoperiosteal flap with a vertical releasing incision distal of the tooth 22, a regular diameter bone-level implant (ASTRA OsseoSpeed, Dentsply Sirona) was placed with good primary stability and a correct prosthetic position/axis. A small closure screw was applied to cover the implant.

The ridge deficiency was augmented with a xenograft (Bio-Oss Collagen, Geistlich Pharma) and the graft was covered with a collagen membrane (Bio-Gide, Geistlich Pharma) to allow for hard tissue formation. The flap was released by splitting the periosteum allowing for a tension-free re-adaptation of the flap. After the suturing (Gore-Tex 5.0, W.L. Gore & Associates, Flagstaff, AZ, USA) the implant was left for submucosal healing for 8–10 weeks.

Antibiotics (amoxicillin 3 × 750 mg for 5 days), painkillers (600 mg ibuprofen if needed), and chlorhexidine mouthrinse (0.2%) were prescribed. The sutures were removed 10 days after implant placement (Fig 2-6-6).

Provisionalization

Two weeks after the abutment connection, an analog impression was taken. In the laboratory, the dental technician fabricated the provisional crown using the temporary abutment (retentive) made from a titanium alloy (TAN) and veneered with a classic acrylic PMMA material (New Outline, Anaxdent) that was later on easy to reline in the yet undercontoured submucosal part. This was partly due to the provisional being fabricated with a kind of ridge flap design, to avoid too much pressure on the soft tissue during insertion.

After removal of the healing abutment, healthy peri-implant mucosa was revealed. The provisional was inserted and tightened. During the following weeks, the provisional was modified two times with composite resin to optimize the emergence profile (Fig 2-6-7).

Impression

After a provisional phase of 5 months, a second impression with an individualized impression coping was taken. This individualized impression coping presented the exact copy of the emergence profile that was sequentially developed with the provisional. In order to modify the standardized impression copings, the provisional was mounted to an analog and embedded in a putty material. Once the material had set the provisional crown could be unscrewed and the impression coping was mounted.

The free space could then be filled with either a light-curing composite or as it was done in this case with a self-curing acrylic (GC Pattern Resin, GC, Leuven, Belgium).

The now individualized impression coping was transferred to the implant sight and the final impression was carried out and sent to the dental laboratory (Fig 2-6-8).

Fabrication of cast and wax-up

The master cast was produced in the laboratory and a wax-up was fabricated using white wax in order to verify the exact shape of the final restoration before the actual restoration and its framework was created (Fig 2-6-9).

Fabrication of the all-ceramic zirconia abutment

As this implant restoration was Part of a clinical study the patient was randomized into the cement-retained customized zirconia abutment group (Atlantis, Dentsply Sirona). Once the conventional impression was translated into a master cast, the models were scanned using a lab scanner (Imetric 4D, Courgenay, Switzerland) and the indicated metal mono scanbody for the Atlantis workflow. The generated files were then uploaded to the Atlantis WebOrder and the color of the abutment was indicated as 00 (uninfiltrated white). The abutment was predesigned by the Atlantis team and then uploaded to their cloud-based Atlantis 3D Editor. Here adjustments like margin lines or other small corrections could be done and the revised abutment was approved for production. Once delivered, the abutment was checked on the cast for its correct emergence profile according to the study protocol; this had to be verified intraorally (Fig 2-6-10).

Fabrication of the all-ceramic abutment crown

After the clinical verification of the abutment in the dental laboratory, an all-ceramic lithium-disilicate crown (IPS e.max press LT A2, Ivoclar Vivadent, Schaan, Liechtenstein) was produced by means of the lost wax technique, and veneered (IPS e.max Ceram, Ivoclar Vivadent) according to the custom shade that was developed by the dental technician in collaboration with the patient.

After two firings, the surface texture and the final shape were developed with stones and diamond burs. The glaze firing was followed by an additional stain firing and a mechanical polishing procedure (Fig 2-6-11).

Integration of the cement-retained implant restoration

The provisional was removed and the implant and adjacent tissues were disinfected with a chlorhexidine solution. After disinfection (Tiutol dent, B. Braun Melsungen, Melsungen, Germany) and the application of a chlorhexidine gel to the submucosal Part (PlakOut Gel, KerrHawe, Bioggio, Switzerland), the zirconia screwretained abutment was tightened with the final torque as recommended by the manufacturer and the screw access hole was sealed with Teflon and a composite filling (Tetric Classic, Ivoclar Vivadent). Once the abutment was seated, the lithium-disilicate crown was adhesively cemented (Multilink Automix yellow, Ivoclar Vivadent). After the cementation, the implant restoration was meticulously checked for any remaining cement excess and thereafter the occlusion was checked and minor adjustments made, followed by polishing.

The final result was extremely pleasing to the entire team and the patient (Fig 2-6-12).

(Dental practitioner: Dr D Büchi; Technician: MDT V Fehmer.)

2.6.2 Anterior implant-supported SC with GBR

■ Anterior single central incisor (metal-ceramic restoration)

■ Single anterior implant with GBR

The following case involves the application of a regular diameter implant (bone level 4.1 mm) with a gold abutment in the esthetic zone.

Assessment and treatment planning

A 47-year-old female patient was referred to the clinic after the extraction of her central incisor 11 performed by the referring dental practitioner due to an accident. Her wish was to receive a fixed restoration.

The patient was healthy, a non-smoker, and did not take any medication; however, she drank a lot of black tea which led to all the palatal staining.

Two treatment options for replacement with a fixed restoration were discussed: a single-retainer resinbonded fixed dental prosthesis (RBFDP) bonded to tooth 21, and a single implant.

Both options were feasible and could have been considered a valuable treatment option.

As both treatment options were discussed and elaborated with the patient, pointing out indications and potential limitations, the patient tended toward replacement by means of a single implant, which was thereafter planned.

After a healing period of 8 weeks, an early implant placement procedure was planned. Due to the position in the arch and the available space, it was decided to place a Straumann BL implant (Straumann, Basel, Switzerland) with a diameter of 4.1 mm, including GBR if needed. After successful osseointegration and a provisional phase, the implant should be restored with a direct screw-retained restoration (Fig 2-6-13).

Implant placement and regeneration

According to the diagnostics, a surgical stent was fabricated transferring the prosthetic plan of the ideal 3D position of the implant to the surgical intervention.

At the day of implant placement (8 weeks after extraction), the patient was pre-medicated with 1500 mg amoxicillin and 600 mg ibuprofen. After the raising of a mucoperiosteal flap with a vertical releasing incision distal of the tooth 12, a regular diameter bone-level implant (Straumann BL 4.1 mm) was placed with good primary stability and a correct prosthetic position/axis. A small closure screw was applied to cover the implant.

The ridge deficiency was augmented with a xenograft (Bio-Oss Collagen, Geistlich Pharma, Wolhusen, Switzerland) and the graft covered with a collagen membrane (Bio-Gide, Geistlich Pharma) to allow for hard tissue formation. The flap was released by splitting the periosteum allowing for a tension-free readaptation of the flap. After the suturing (Gore-Tex 5.0, W.L. Gore & Associates, Flagstaff, AZ, USA) the implant was left for submucosal healing for 8–10 weeks.

Provisionalization

Two weeks after the abutment connection, an analog impression was taken. In the laboratory, the dental technician produced the provisional crown using the temporary abutment (retentive) made from a titanium alloy (TAN) and veneered with a classic acrylic PMMA material (New Outline, Anaxdent, Stuttgart, Germany) that was later on easy to reline in the yet undercontoured submucosal part. This was due to the provisional having a kind of ridge flap design to avoid too much pressure on the soft tissue during insertion.

After removal of the healing abutment, healthy peri-implant mucosa was revealed.

The provisional was inserted and tightened. During the following weeks, the provisional was modified two times with composite resin to optimize the emergence profile (Fig 2-6-15).

Impression

After a provisional healing phase of 5 months, a second impression with an individualized impression coping was taken (Fig 2-6-16).

Fabrication of the screw-retained implant restoration

The master cast was produced in the laboratory. A wax-up was fabricated using esthetic wax in order to verify the exact shape of the final restoration before the actual restoration, and a framework was created (Fig 2-6-17).

The custom shade was developed by the dental technician during the wax-up try-in. In this particular case, because of the general low value and grayish appearance of the reference teeth, it was decided that a metal-based restoration would serve as the restorative material of choice. Despite the fact that those abutments are quite expensive and the process of casting always comes with additional risks and costs associated by the alloy, it was considered the most predictable restorative material. Once the abutment was cast, it was checked on the cast for its correct anatomical support and directly veneered (Creation Classic CC, Willi Geller, Meiningen, Austria) according to the custom shade. After two dentin firings, the surface texture and the final shape were developed with stones and diamond burs, before a biscuit bake try-in was carried out.

Biscuit bake try-in

The biscuit bake was clinically checked with respect to its fit and shape of the central incisor.

The patient and the restorative team were already very satisfied with the final shape and gingival adaptation.

However, small details could still be improved. So it was discussed to slightly shorten the distal incisal edge, push the tissue a bit more toward the mesial papilla and try to copy the superficial characteristics by means of some white spots toward the incised third and brown staining in the cervical area.

The aforementioned detail is crucial to the final treatment’s success but difficult to apply toward the laboratory work if the technician cannot be on site themselves. The use of images is clearly of great support but they will never lead to the same ideal outcome (Fig 2-6-18).

Finalization of the restoration

The shape was adjusted as discussed during the biscuit bake try-in and glaze firing was followed by an additional stain firing to achieve the perfect adaptation of stains. Finally, the crown was mechanically polished to achieve a similar degree of gloss to the adjacent central incisor.

Integration of the screw-retained implant restoration

After 2 weeks, the abutment/crown screw was retightened with the final torque as recommended by the manufacturer (35 Ncm). For the final closure of the screw access, rubber dam was applied, and the veneering ceramic layer around the access hole was etched (9% hydrofluoric acid) and silanated (Monobond Plus, Ivoclar Vivadent). The screw was densely covered with Teflon. Subsequently, a bonding agent was applied (Heliobond, Ivoclar Vivadent), and the closure of the screw access hole was finalized with a light-curing composite filling material (Tetric Classic, Ivoclar Vivadent) in the corresponding shade. After the light-curing, the occlusion was checked, followed by polishing of the composite filling.

The final result was extremely pleasing for the entire restorative team and even more importantly, the patient was very satisfied that this long treatment had paid off so well (Fig 2-6-19).

(Surgeon: Prof Dr R Jung; Dental practitioner: PD Dr S Mühlemann; Technician: MDT V Fehmer.)

2.6.3 Anterior implant-supported SC

■ Anterior regions (titanium-resin-base/hybrid abutment and restoration)

The following case involves the application of a narrow-diameter implant in the esthetic zone.

Assessment and treatment planning

A 51-year-old female patient presented herself at the clinic because of slight pain from time to time in the region of tooth 12. The patient was healthy, a non-smoker, and did not take any medication. During the clinical examination, she complained about a light pain on percussion on tooth 12. The tooth was endodontically treated and restored with a composite build-up. Further, the tooth showed an increased mobility of grade 2 with no periodontal probing depth (PPD) of more than 4 mm. The periapical radiograph showed radiolucency around the apex of tooth 12. After consultation with an endodontic specialist, it was decided to extract tooth 12 and to perform a ridge preservation procedure to maintain the volume. After a healing period of 8 weeks, an early implant placement procedure was planned. Due to the fact that the distance between the teeth 11 and 13 was narrow (approximately 6 mm), it was decided to place a Straumann bone level tapered (BLT) implant (Straumann, Basel, Switzerland) with a diameter of 2.9 mm, including GBR if needed. After successful osseointegration and a provisional phase, the implant was to be restored with a translucent zirconia (Katana Zirconia, STML A2 T18; Kuraray, Tokyo, Japan) crown on a titanium bonding base. It was planned to take an analog impression and then to follow a digital laboratory workflow using computer-aided design/computer-aided manufacturing (CAD/CAM) technology (Fig 2-6-20).

Surgical procedure

The tooth was extracted and a xenogeneic bone substitute in combination with a punch graft from the palate was used to perform a ridge preservation procedure (Fig 2-6-21). A provisional removable prosthesis was adapted and incorporated to replace the missing tooth.

Six weeks later, a well-maintained ridge with completely healed soft tissue conditions could be observed clinically. Alginate impressions of the situation were made and a wax-up of tooth 12 was fabricated on the plaster cast. According to the wax-up, the dental technician manufactured a conventional surgical guide (Fig 2-6-22).

On the day of implant placement (7 weeks after extraction), the patient was premedicated with 1500 mg amoxicillin and 600 mg ibuprofen. Under local anesthesia, a crestal incision from the palatal line angle of tooth 11 to the palatal line angle of tooth 13 and a vertical releasing incision distal at tooth 13 was performed. A full-thickness flap was elevated. The conventional surgical stent was placed and the preparation of the implant bed was performed according to the manufacturer’s instructions as follows: at the beginning, the implant position was marked with a 1.4-mm round bur. The first osteotomy was performed with the needle drill with a diameter of 1.6 mm. Afterwards, the implant bed was prepared with the pilot drill with a diameter of 2.2 mm (Fig 2-6-23a to 2-6-23e). The correct axis and the vertical position were checked with the help of the specific indicators and the use of the surgical guide. As the bone was quite soft, there was no need to use the profile drill and the tap. A Straumann BLT Small CrossFit (SC) implant with a diameter of 2.9 mm and length of 12 mm was placed with good primary stability and a correct prosthetic position/axis. A small closure screw was applied to cover the implant. Autologous bone chips, a xenograft, and a collagen membrane were used to augment the buccal fenestration defect and to enhance the vestibular ridge contour for a more natural appearance of the final crown. The periosteum was released and the flap was repositioned to achieve a primary wound closure with a 5.0 ePTFE non-absorbable monofilament suture (Fig 2-6-23). Antibiotics (amoxicillin 3 × 750 mg for 5 days), painkillers (600 mg ibuprofen if needed), and chlorhexidine mouthrinse (0.2%) were prescribed. The sutures were removed 10 days after implant placement.

The healing period was uneventful and 3 months after surgery the clinical examination revealed healthy tissues. At this time point, the abutment connection was performed under local anesthesia. The soft tissue covering the implant was de-epithelialized using a round diamond bur. A U-shaped incision was performed and the small flap over the implant was raised. A small tissue pouch was prepared at the buccal aspect of the implant and the flap was rotated into it. After removal of the closure screw, a healing abutment with a gingival height of 3.5 mm was inserted (Fig 2-6-24).

Prosthetic procedure

Two weeks after the abutment connection, an analog impression was taken. In the laboratory, the dental technician produced the provisional crown using the temporary abutment made out of a titanium alloy (TAN) and composite resin. The provisional had a kind of ridge-lap design to avoid too much pressure on the soft tissue during insertion. After removal of the healing abutment, healthy peri-implant mucosa was present. The provisional was inserted and tightened with 15 Ncm. During the following weeks, the provisional was modified two times with composite resin to optimize the emergence profile. In addition, it was used to apply pressure on tooth 11 because it was the patient’s wish to close the diastema (Fig 2-6-25).